Emotional Automaticity Is a Matter of Timing
There has been a long controversy concerning whether the amygdala's response to emotional stimuli is automatic or dependent on attentional load. Using magnoencephalography and an advanced beamformer source localization technique, we found that amygdala automaticity was a function of time: while early amygdala responding to emotional stimuli (40-140 ms) was unaffected by attentional load, later amygdala response (280-410 ms), subsequent to frontoparietal cortex activity, was modulated by attentional load.
Available from: David N. Silverstein
- "A recent study found that neurons in the macaque pulvinar can respond selectively to snakes in 55 ms (Van Le et al., 2013), which is likely too short for a cortical route. It has also been found that the amygdala can be activated with low latencies from a fear-relevant stimulus in about 40–120 ms (Luo et al., 2010), perhaps along the low road. While dual pathways were initially observed in rats, there is functional evidence this applies to primates and specifically humans (Rudrauf et al., 2008; Garrido et al., 2012; Garvert et al., 2014) as well. "
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ABSTRACT: A hypothesis is proposed for five visual fear signaling pathways in humans, based on an analysis of anatomical connectivity from primate studies and human functional connectvity and tractography from brain imaging studies. Earlier work has identified possible subcortical and cortical fear pathways known as the “low road” and “high road,” which arrive at the amygdala independently. In addition to a subcortical pathway, we propose four cortical signaling pathways in humans along the visual ventral stream. All four of these traverse through the LGN to the visual cortex (VC) and branching off at the inferior temporal area, with one projection directly to the amygdala; another traversing the orbitofrontal cortex; and two others passing through the parietal and then prefrontal cortex, one excitatory pathway via the ventral-medial area and one regulatory pathway via the ventral-lateral area. These pathways have progressively longer propagation latencies and may have progressively evolved with brain development to take advantage of higher-level processing. Using the anatomical path lengths and latency estimates for each of these five pathways, predictions are made for the relative processing times at selective ROIs and arrival at the amygdala, based on the presentation of a fear-relevant visual stimulus. Partial verification of the temporal dynamics of this hypothesis might be accomplished using experimental MEG analysis. Possible experimental protocols are suggested.
Frontiers in Systems Neuroscience 08/2015; 9(101). DOI:10.3389/fnsys.2015.00101
Available from: Marco Tamietto
- "). Because both early nonconscious and later conscious responses take place within the time window of a single volume acquisition in fMRI studies, the different functional values of neural activity in the same structure may be integrated or overridden (Brosch & Wieser, 2011; Costa et al., 2014; Luo et al., 2010). This limitation of fMRI has been partially circumvented by the use of methods with a better temporal resolution, such as electroencephalography (EEG) or magnetoencephalography (MEG), which have a temporal resolution on the order of milliseconds , but, on the other hand, have a poor spatial resolution and have been questioned when used to detect neural activity in subcortical structures (Andino, Menendez, Khateb, Landis, & Pegna, 2009; Cecere et al., 2014; de Gelder et al., 2002; Rossion et al., 2000). "
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ABSTRACT: Following destruction or denervation of the primary visual cortex (V1) cortical blindness ensues. Affective blindsight refers to the uncanny ability of such patients to respond correctly, or above chance level, to visual emotional expressions presented to their blind fields. Fifteen years after its original discovery, affective blindsight still fascinates neuroscientists and philosophers alike, as it offers a unique window on the vestigial properties of our visual system that, though present in the intact brain, tend to be unnoticed or even actively inhibited by conscious processes. Here we review available studies on affective blindsight with the intent to clarify its functional properties, neural bases and theoretical implications. Evidence converges on the role of subcortical structures of old evolutionary origin such as the superior colliculus, the pulvinar and the amygdala in mediating affective blindsight and nonconscious perception of emotions. We conclude that approaching consciousness, and its absence, from the vantage point of emotion processing may uncover important relations between the two phenomena, as consciousness may have evolved as an evolutionary specialization to interact with others and become aware of their social and emotional expressions.
Copyright © 2015 Elsevier Inc. All rights reserved.
Consciousness and Cognition 06/2015; 36. DOI:10.1016/j.concog.2015.05.007 · 2.31 Impact Factor
Available from: Arnoud Arntz
- "It is unlikely that this result was due to floor effects, as there was a substantial degree of variation in correctly identified RMET stimuli across participants. However, the absence of group differences might be explained by other artifacts in our experimental set-up, such as the possibility that our stimulus duration was too long in order to tap into early stages of information processing (Luo et al., 2010). Alternatively, psychopaths might have kept the image of the eyes in visual shortterm memory, still enabling the engagement in slower, cognitive strategies for identifying mental states. "
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ABSTRACT: Theory of Mind (ToM) is a social perceptual skill that refers to the ability to take someone else's perspective and infer what others think. The current study examined the effect of potential hostility biases, as well as controlled (slow) versus automatic (fast) processing on ToM performance in psychopathy. ToM abilities (as assessed with the Reading the Mind in the Eyes Test; RMET; Baron-Cohen, Wheelwright, Hill, Raste, & Plumb, 2001), was compared between 39 PCL-R diagnosed psychopathic offenders, 37 non-psychopathic offenders, and 26 nonoffender controls. Contrary to our hypothesis, psychopathic individuals presented with intact overall RMET performance when restrictions were imposed on how long task stimuli could be processed. In addition, psychopaths did not over-ascribe hostility to task stimuli (i.e., lack of hostility bias). However, there was a significant three-way interaction between hostility, processing speed, and psychopathy: when there was no time limit on stimulus presentation, psychopathic offenders made fewer errors in identifying more hostile eye stimuli compared to nonoffender controls, who seemed to be less accurate in detecting hostility. Psychopaths' more realistic appraisal of others' malevolent mental states is discussed in the light of theories that stress its potential adaptive function.
Copyright © 2015. Published by Elsevier Ltd.
International Journal of Law and Psychiatry 02/2015; 38. DOI:10.1016/j.ijlp.2015.01.012 · 1.19 Impact Factor
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